Influence of data conversion methods from torsion tests on the Garofalo equation parameters for a high nitrogen steel

Torsion tests in the temperature range 900 to 1 200 degrees C and strain rates varying from 0.005 to 5 s(-1) for a high nitrogen steel were analyzed. The influence of various conversion methods from torsion tests on the stress-strain curves and on the Garofalo equation parameters as a function of strain was studied for this steel. In addition, the creep behavior of the high nitrogen steel was analyzed using the Garofalo equation. The high values of the activation energy and stress exponent using the peak stress are attributed to the microstructure that changes strongly during the first stages of deformation. The analysis of the Garofalo parameters allowed determination of a steady state at strains of about 2.5. At this strain, the values of the activation energy and the stress exponent correlated well with slip creep mechanisms operating in other reinforced steels at high strain rates.